Thanks for writing in to Healthcare Magic!
The only method by which fluclox can cause this is a gastritis
, if you have a history of acid peptic disorder then it is the cause otherwise fluclox can not cause chest pain
Another possibility is some separate pathology like spread of the infection to chest, pneumonia
You need evaluation and investigation under the advise of a physician.
If you have any further query please let me know I would try to answer it for you.
Wish you a great health!